title: Pyrimidine-4-carb-oxy-lic acid.
abstract: The crystal structure of the title compound, C5H4N2O2, is built of acid mol-ecules located on a mirror plane. They form sheets stacked along the b-axis direction. The mol-ecules inter-act via O-H⋯N hydrogen bonds, forming [001] chains, and weak van der Waals inter-actions.
authors.affiliation: Institute of Nuclear Chemistry and Technology, ul. Dorodna 16, 03-195 Warszawa, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kiegiel
authors.forename: Wojciech
authors.initials: W
authors.lastname: Starosta
authors.forename: Janusz
authors.initials: J
authors.lastname: Leciejewicz